Proximity check helps you find assets that are spatially close but not topologically connected, which typically are a consequence of a data entry or import error.
Proximity check is a data quality and clean-up feature in epanet-js. Its main purpose is to find components in your model that look right visually but are not connected in the network's topology.
This problem is extremely common when importing data from a GIS. Proximity check finds where junctions are near a pipe but isn't actually "snapped" to it, meaning the model doesn't know they are connected.
If not fixed, these proximity errors may break your hydraulic simulation or produce highly inaccurate results:
The hydraulic solver relies on a perfectly connected network to calculate how flow and pressure move. A node that isn't connected to a pipe—even if it's 1mm away—is "invisible" to the solver.
Proximity check works by scanning your model and flagging nodes that are within a specified distance of pipes.
epanet-js will generate a list of potential issues for review. Selecting an issue from this list will center the map display on the involved assets. It’s then the user's responsibility to inspect the issue and take one of two actions:
A good workflow is to start with a very small distance, such as 0.1 m. Review the issues that appear, fix the ones that need fixing, and clear out the obvious false positives. Once that list is clean, gradually increase the distance and repeat the process.
By stepping the distance up slowly, you avoid being overwhelmed by a massive list of potential issues all at once. Instead, you work through the real problems first, then expand outward until the remaining items are things that genuinely don’t need to be connected. This approach keeps the review manageable and helps you clean up your network much more efficiently.